MODERN PHYSICS , 



(A lecture delivered at the Fifth Midwinter 

 Convention of the American Institute of Elec- 

 trical Engineers, New York, Feb. 15, 1917) 



BY 



R. A. MILLIKAN 

 Professor of Physics, Chicago University 



Let me run over a list of ten discoveries which I will 

 call the ten most important advances [in physics] of the 

 last twenty years. 



We may aptly characterize the physics of the last twenty 

 years as the physics of atomism, and the first discovery 

 on my list of ten advances is the recent verification of the 

 adumbrations of the Greeks regarding the atomic and the 

 kinetic theories the proof that, as Democritus had im- 

 agined 500 B. C, this world does indeed consist, in every 

 part of it, of matter which is in violent motion. 



Up to within six years there were not a few distin- 

 guished scientists who withheld their allegiance even from 

 these atomic and kinetic theories of matter. The most 

 illustrious of them was Professor Wilhelm Ostwald, but 

 in the preface to a new edition of his Outlines of Chem- 

 istry he now says frankly: 



"I am convinced that we have recently become pos- 

 sessed of experimental evidence of the discreet or grained 

 nature of matter for which the atomic hypothesis sought 

 in vain for hundreds and thousands of years. The isola- 



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